About 98,000 California families must verify their immigration status by Sept. 30 or lose their health coverage, the state’s insurance exchange announced Thursday.

In a statement, Covered California, which sold nearly 1.4 million policies in late 2013 and early 2014, said that nearly 100,000 families provided inconsistent documentation during the application process and “will need to submit documents showing they are lawfully present in the United States as U.S. citizens, U.S. nationals or individuals with eligible immigration status.”

Those who do not get the job done by the end of the month “risk termination of health coverage.”

The pain could also be financial. About 90 percent of all Covered California policy holders received a subsidy from the government that is also at risk of refund.

“If you have received tax credits, and your health insurance is canceled, you may have to repay those tax credits. If your health insurance is canceled, you may also have to pay a tax penalty,” said Peter Lee, Covered California’s executive director, in Thursday’s statement.

The Affordable Care Act, which requires most Americans to get coverage or pay a tax penalty in 2015, mandates that all who buy policies through exchanges be “lawfully present” residents.

The Covered California application asks each applicant whether or not he or she is a “U.S. Citizen or U.S. National.”

If they’re not, they can still receive coverage if they have paperwork that shows they have “satisfactory immigration status” in one of 21 categories that range from green card holders and asylum seekers to refugees and battered spouses.

The application asks for identification numbers and other information to verify that status, but not for the actual documents themselves.

Basic information is then transmitted to federal databases for verification. In about 98,000 cases, the information on the form didn’t match what was in the database.

James Scullary, a spokesman for the exchange, said that about 92,000 of those did not respond to an initial request for clarification. About 6,000 provided more information, but it still didn’t clear up the immigration status.

“An example might be, lets say somebody has stated they have three children but sent in only two birth certificates,” Scullary said.

He said the law generally gives the exchange up to 90 days to verify immigration status but also grants some leeway beyond that three-month time frame.

“We have provided some time because we wanted to make sure that everyone gets covered, but we have to move forward and get these cases cleaned up,” Scullary said.

The problem is not restricted to California. In mid-August the Centers for Medicare and Medicaid Services said that there were about 450,000 cases nationwide where discrepancies existed, and about 310,000 have not responded to calls for more information.

Covered California is mailing and emailing notices to affected families starting this week.

The notices will include instructions on how to upload needed documents to the exchange’s website or submit them by fax. Certified insurance agents and enrollment counselors can also help with the process.

The main documents used to prove U.S. citizenship or nationalization are: A U.S. passport, a certificate of naturalization or citizenship or certain tribal documents for federally-recognized Indian tribes.

In addition, combinations of other documents, like a U.S. birth certificate and a valid driver’s license, or a military record showing birthplace and a school identification card, can also be used.

A full list of qualifying documents is posted on Covered California’s website at coveredca.com.